The present invention relates to mobile communications systems and, more particularly, to addressing and mobility management techniques in such systems that may include multimedia applications in a highly dynamic Internet Protocol-based networking environment.
Several important mobility management issues need to be addressed in designing a communications system wherein the system is characterized by a dynamic network topology (e.g., mobile system access points or network nodes) and a relatively large number of mobile end users. Particularly, critical among them are issues such as: keeping track of mobile end users and access point locations in the system (i.e., location management); reaching and initiating communications with a mobile end user (i.e., mobile access); and continuity of service when a mobile end user moves between coverage areas associated with different system access points (i.e., handoff management). Existing networks have attempted to provide solutions to these problems in their specific domains. For example, limited solutions have been provided by Cellular Digital Packet Data (CDPD) networks, Cellular/Personal Communications Services (Cellular/PCS) systems, and Mobile Internet Protocol (mobile IP) networks. However, there are several known limitations to these conventional approaches owing to the fact that they were designed for different operating conditions.
A new multimedia mobile network that advantageously addressed the above and other issues while reducing and/or eliminating the drawbacks associated with the above-mentioned existing networks was disclosed in three U.S. patent applications identified by Ser. No. 09/191,133 (entitled: xe2x80x9cSubnetwork Layer for a Multimedia Mobile Networkxe2x80x9d); Ser. No. 09/191,132 (entitled: xe2x80x9cAddressing Scheme for a Multimedia Mobile Networkxe2x80x9d); and Ser. No. 09/191,134, now U.S. Pat. No. 6,160,804 (entitled: xe2x80x9cMobility Management for a Multimedia Mobile Networkxe2x80x9d), all concurrently filed on Nov. 13, 1998, the disclosures of which are incorporated by reference herein. The multimedia mobile network described in the above applications provides a network architecture and mobility management techniques that yield an efficient, scalable, and flexible communications system capable of handling various applications including multimedia applications.
Given a network with an architecture and mobility management techniques such as are associated with the above-mentioned multimedia mobile network, it would be highly desirable to provide methods and apparatus for implementing an improved Internet Protocol-based mobile network such as, for example, one that may be employed in accordance with an IPv4 standard. The IPv4 standard is described in J. Postel, xe2x80x9cInternet Protocol,xe2x80x9d RFC 791, USC/Information Science Institute, September 1981, the disclosure of which is incorporated herein by reference.
The present invention provides addressing techniques and various mobility management methodologies, as well as apparatus for implementing them, in an Internet Protocol (IP) based mobile communications system. These techniques and methodologies are capable of supporting various voice and data services including, for example, multimedia services. The methods and apparatus are particularly well-suited for implementation in accordance with the IPv4 standard.
In one IP addressing aspect of the invention, a method for use in an Internet Protocol (IP) based communications system, comprises the steps of: (i) assigning a temporary location IP address (e.g., LIPA) to a mobile user station in the communications system, the address being a combination of an identifier of the mobile user station (e.g., MID) and an identifier of a network node in the communications system with which the mobile user station is currently associated (e.g., RID); and transferring packets to and from the mobile user station in accordance with the temporary location IP address. The method may further comprise the step of changing the temporary location IP address assigned to the mobile user station when the station becomes associated with another network node of the communications system, the changed address being a combination of the identifier of the mobile user station and an identifier of the new network node. The method may further comprise the step of assigning a location IP address to a network node in the communications system, the address being a combination of an identifier of the network node and a common identifier of mobile user stations in the communications system.
In another IP addressing aspect of the invention, a method for use in facilitating transfer of packets in an Internet Protocol (IP) based communications system, wherein the communications system includes a plurality of network nodes and a plurality of mobile user stations, comprises the steps of: (i) inserting an address option field in a packet header of a packet to be transferred in the communications system, the address option field including supplemental address related data for facilitating transfer of packets in the communications system; and (ii) processing the packet within at least one of a network node and a mobile user station in the communications system in accordance with the supplemental address related data in the address option field of the packet header. The address option field may comprise an address type field, an address length field and an address data field. Various address related data may be included in the address data field to facilitate transfer of packets in an IP-based communications system.
In a mobility management aspect of the invention, several unique mobility management control messages are defined for use in performing various mobility management functions in the communications system with respect to the mobile user stations and network nodes. These messages may comprise: (i) a Location Update Message (LUM); (ii) a Location Confirm Message (LCM); (iii) a Location Query Message (LQM); (iv) a Location Reply Message (LRM); (v) a Registration Message (RM); and (vi) a Registration Reply Message. One or more of these messages are used in the IP-based system to perform mobility management functions such as location management, mobile access and in-call mobility management.